I wasn't criticising you, Art, I was only suggesting that the original topic was the question about what to listen to in the earlier period. And I was struck by how haphazard it is currently -- which is, I completely agree, partly a virtue -- at least in my experience, to get a practical sense of the history. And parts of it are diagrammable, people are diagramming it all the time in conversation. I have heard it done by trad people who say X learned from Y, Y came from this part of Appalachia where they tended to play like this. That is a kind of diagram.

Jazz is all over the place too, but there are a number of reputable introductions and practical surveys -- this is what the music is doing here, this is how this orchestra or whatever did what they did -- which give people some kind of frame. It is open to abuse, obviously, but so is everything. My not very radical suggestion was to bring the bare facts as a starting point into a useful format. yours, Peter T.